The present invention relates to a flash memory card having a flash memory mounted on a card as a memory medium.
Attention has been paid to flash memories (flash EEPROMS) as semiconductor memories that will replace magnetic disks such as hard disks and floppy disks. A flash memory is a nonvolatile, low-power-consumption semiconductor memory which can be electrically reprogrammed. Since these memories are compact, lightweight, and highly resistant to vibrations, the application range of the memories in portable devices and the like extends.
Such flash memories find a typical application in flash memory cards. A flash memory card is a card obtained by mounting one or a plurality of flash memories (IC chips) on one card. This card is generally provided as a PC card complying with PCMCIA.
A PC card needs to have card attribute information referred to as CIS (Card Information Structure) information that displays or describes the configuration of the card, the manner of accessing the card, and the like, owing to the PCMCIA requirements (specifications) that the compatibility of the card should be improved between host computers (e.g., personal computers) complying with the standards.
On a flash memory card of this type, the following components are mounted, in addition to a flash memory: a controller connected to a host system through a predetermined interface to execute data read/write operations with respect to the flash memory on the card; a ROM which holds programs required for the operation of the controller and a RAM for holding data; and the like.
In a conventional flash memory card of this type, CIS information is stored in the ROM on the card, together with other software programs. When the flash memory card is inserted into the card slot of the host system, the host computer searches for the CIS information of this flash memory card. In the flash memory card, the controller reads out the CIS information from the ROM and sets it in the RAM or register that the host computer can directly access. The host computer assigns a memory space, an I/O space area, an interruption level, and the like to the card on the basis of the CIS information loaded from the flash memory card, and sequentially read/write-accesses the flash memory on the card afterward.
In some case, part or all of the CIS information of the flash memory card must be rewritten. When, for example, flash memory cards manufactured by a card maker as a primary supplier are to be distributed as cards provided a card vendor as a secondary supplier, pieces of attribute information such as product maker information, product name information, and product version of the CIS information of each card need to be updated.
In a conventional flash memory card, however, since the CIS information is stored as fixed information in the ROM as described above, it is practically impossible to rewrite the CIS information.
Note that the conventional flash memory card does not have the function of protecting the data stored in the flash memory, i.e., the write protect function of inhibiting new data from being written in the flash memory. For this reason, new data may be overwritten in the flash memory card in which data to be retained is stored. As a result, the important data may be erased.
Further, in a flash memory card wherein a flash memory unit is detachable to an adapter, the contents of CIS must be changed in accordance with the flash memory body.